Fundamentally, a depressed brain looks pretty much like any other brain. In fact, there’s no brain scan, MRI, EEG or any other medical test that can definitively diagnose depression, and it’s not understood in detail like other brain disorders. While we know the neurochemicals involved and many contributing factors, the truth is we really don’t know the neural causes of depression or what’s a cause and what’s a symptom even.
At the most basic level, depression is just the routine activation of certain brain circuits, which we all have, in specific patterns that result in depressive symptoms in a person.
In the book, The Upward Spiral: Using Neuroscience to Reverse the Course of Depression, One Small Change at a Time, Alex Korb explains depression like this:
The flow of traffic through a city is complex and dynamic – sometimes jamming up inexplicably and other times flowing smoothly, even at rush hour. The stock market and larger economy follow similar patterns as does the weather and even pop culture. Mathematically, these types of complex dynamic systems share many similarities, including the way the whole system — whether a traffic jam, a tornado, a recession or recovery, a viral tweet, or the next fad — can get caught in a runaway pattern: either an upward or downward spiral.
So why do tornadoes happen in Oklahoma but not in New York? Because conditions are just right — the flatness of the land, temperature changes, humidity, and wind direction and speed. But there’s nothing wrong with Oklahoma.
The same is true of your brain. In depression, there’s nothing fundamentally wrong with the brain. It’s simply that the particular tuning of neural circuits creates the tendency toward a pattern of depression. It has to do with the way the brain deals with stress, planning, habits, decision making, and a dozen other things — the dynamic interaction of those circuits. And once the pattern starts to form, it causes dozens of tiny changes throughout the brain that create a downward spiral.
A Depressed Brain Isn’t Damaged Goods
We all have the same basic brain structure although the neuronal connections, determining the activation of and communication between brain circuits, are unique to every person. The particular circuits excited over and over in your brain become the go-to default pattern for you and are the product of your thoughts, interactions with others and the world, and the events that happen to you.
In the 1960s, we were told depression was due to a deficiency of the neurotransmitter norepinephrine. Then, a still popular theory blamed depression on too little serotonin. Today, we know that it’s much more complicated than either of these and involves many other neurochemicals which influence and are influenced by depression. (For example: dopamine, oxytocin, GABA, melatonin, endorphins, endocannaboids) To oversimplify, each neurotransmitter tends to contribute to a particular depressive symptom.
How Does A Brain Get Depressed?
So, depression is attributed to a specific pattern of activated circuits in your brain and how they’re impacting each other, but how does this tendency take shape? There are many factors which contribute to forming depressive patterns:
Genetics – Genes aren’t your destiny by any means, but they do guide the initial development of your brain circuitry. You can inherit a brain more that’s more likely to become depressed. Research has determined that there’s a genetic component to depression and that as much as 40% of people with depression have a genetic link. If a person has a parent or sibling that has had major depression, they are three times more likely to develop the condition which may be due to both hereditary and environment. Women have a 42 percent chance of hereditary depression, while men only have a 29 percent chance.
Early Childhood – Your childhood experiences literally shape your brain. While genes supply the basic blueprint for brain development, experience tweaks brain circuitry, and young brains in a critical window of development are particularly sensitive. Stressful or traumatic events in childhood and adolescence dictate the development of neural circuitry and influence the levels of chemicals released in the brain having powerful and lasting effects. The prefrontal cortex of the brain doesn’t finish maturing until a person is in their twenties and is susceptible to stress the whole time.
Stress – The current level of stress in your life is a big factor affecting which circuits are activated in the brain. Stress can disrupt a person’s healthy behaviors starting the brain on a downward slide. For example, stress at work can lead to working longer hours, which leads to missing exercise and yoga for weeks and not hanging out with friends or having much time for your partner which puts you in a funk and causes troubles in the relationship which only leads to more stress which means losing sleep and binge eating etc… You get the idea. Recent research has also shown that chronic high stress kills neurons and prevents the birth of new brain cells in a region called the hippocampus which is necessary for a healthy stress response.
Social Support – Humans are social beings who need each other and are meant to be around other people. Numerous studies have shown that close reationships protect against depression. In research, low self-rated social support was associated with higher levels of anxiety and depression. In another study involving depressed college students, lack of perceived social support, described as feeling unappreciated, unloved and uninvolved with family and friends, proved to be one of the most powerful predictors of persistent suicidal thoughts, even in the absence of other risk factors.
Luck – (or lack of it) Yes, randomness plays a part here. Korb writes:
That might be hard to hear, but it’s true. Complex systems, like your brain, are influenced by tiny fluctuations. This explains why on some days there’s a traffic jam and on other days cars flow smoothly. It explains why some YouTube videos go viral, and others remain in obscurity. And it explains why you feel great on some days and crappy on others….
Every brain has depressive tendencies and the potential to become depressed. But, the good news is every brain has wellness tendencies too. Just as a small change can start a brain spiraling down into depression, even a small shift can alter the balance, have a major impact, and begin an upward spiral too.
Changing the timing of a single stoplight may cause or prevent a traffic jam. A YouTube video may go viral from a single tweet. And sometimes tweaking the tuning of one brain circuit can start to reverse the course of depression.
image source: https://www.flickr.com/photos/genphys/